The invention concerns a device for manipulating an object for loading and unloading a clean room, with a housing open toward the clean room, consisting of a stationary outer piece and an inner piece which can be telescopically extended from the latter, which contains a receptacle element for the object in its cover zone, which can be adjusted between at least two levels, one above the other, and lowered into the inner piece, while one level is used for ergonomic insertion of the object and the other serves for access to the object when loading and unloading the clean room, and the outer as well as the inner pieces of the housing are provided with air exit openings in the wall of the housing away from the clean room.
Such a device is known, for example, from DE 4,425,208 C2.
In the SMIF boxes preferably used as hoppers for production of semiconductor chips, the manipulating of the wafer hoppers contained in these boxes always requires at first an opening of the boxes before taking out the hoppers and, at the end of the processing step, their return and the closing of the box The technical solution long since known for this calls for the box to be placed on an opening mechanism of a housing, which encloses a local clean room. Box and opening mechanism have mutually adapted closure elements which can be opened one above the other at the same time, so that dust particles lying on the closure elements on the outside are enclosed in between, when the wafer hopper is lowered along with the two closure elements into the enclosure.
Other opening mechanisms for such SMIF boxes lift the hood of the box in order to grant access to the hopper on the inside. The space created around the hopper is surrounded by pieces of the side wall that also move, down to an access opening, in order to prevent particles from entering.
It is known by DE 4,332,657 C2 how to lift and put back the box hood of the SMIF box with a framelike lifting plate of a lifting mechanism. A fixed support plate, on which the bottom of the transport box can be placed, is inserted into the frame opening, which is configured such that it can accommodate the bottom of the transport box.
It is a disadvantage that the displacement flow arrangement described in this patent cannot meet the high demands of a clean room, since the flow of clean air through the zone of the lifting mechanism and air lock is not provided with the effectiveness that is necessary for sufficient removal of particles under heightened clean room requirements. A continual flushing of the spindle is rather unlikely. Since the upward vertical movement of the lifting element causes a displacement of air and associated vortex effects, the clean room conditions are negatively influenced by a largely uncontrolled spread of particles. Thus, particles generated especially in the lower spindle region can be caught up by the vortices and get into the clean room. The overpressure which prevails hardly counteracts this negative effect The slot provided in the location between the two spaces, acting on the spindle in limited manner in time and space, is not able to effectively allow the resulting particles to escape, especially since zones of relative calm arise in the overall region of the lifting mechanism, so that the particles can again settle there.
Furthermore, it may be disadvantageous to always put down the SMIF box at the height of the loading and unloading opening. If the loading and unloading opening is at an unfavorable height, ergonomic working conditions are no longer assured.
On the other hand, a device according to DE 4,425,208 C2 is preferable, by which the removal of the hopper from the SMIF box occurs by lowering the hopper from the opened SMIF box into a mini-lean room. The device is further outfitted with a grip device for moving the hopper around.
The mini-clean room is formed by an inner piece of a housing, which can extend telescopically from an outer stationary piece of the housing and which contains a receptacle element for a loading and unloading device. The receptacle element can move between at least two levels one above the other. At the rear wall away from the clean room, the loading and unloading device is provided with a unit comprising a filter and a blower, and the outer as well as inner piece of the housing are provided with openings.
The air conditioning of this familiar device ensures an active horizontal low-turbulence air flow during the insertion of the workpiece.
Disadvantageous, however, are the relatively high hardware expenses for the active air conditioning, the vertical movement of the receptacle element of the loading and unloading station, and the hopper lowering device.
U.S. Pat. No. 5,810,537 also describes an opening device whereby the box hood can be raised and lowered again by means of a frame. Unlike DE 4,332,657 C2, the opening formed around the hopper when raising the box hood is enclosed by flexible pieces of side wall, preferably in the form of a bellows, which is joined to the frame and the receiving plate for the bottom of the box.
Also disadvantageous here is the not sufficiently solved problem of ensuring the clean room requirements.
The xe2x80x9cbagxe2x80x9d pulled on forms a space enclosed down to the access opening, which due to the overpressure usually prevailing in the processing system has uncontrolled vortices of air moving through it, so that particles carried along with the air flow settle inside the space bounded by the side walls. This is especially troublesome when the side wall surface is further enlarged by ledges of the bellows.
The object of the invention is to reduce the hardware expenses for the vertical adjustment of the receptacle element of the loading and unloading station, the lowering device of the hopper, and the air conditioning, while maintaining the ergonomic advantages, and to further improve the clean room conditions in the mini-clean room.
According to the invention, the object is accomplished by a device for manipulating an object for loading and unloading a clean room, with a housing open toward the clean room, consisting of a stationary outer piece and an inner piece which can be telescopically extended from the latter, which contains a receptacle element for the object in its cover zone, which can be adjusted between at least two levels, one above the other, and lowered into the inner piece. Whereas one level is used for ergonomic insertion of the object and the other serves for access to the object when loading and unloading the clean room. Both the outer as well as the inner piece of the housing are provided with air exit openings in the wall of the housing away from the clean room. For the telescopic extension of the inner piece and for the lowering of the receptacle element into the inner piece, a common guide rail and a common drive for the inner piece and the receptacle element are provided, while the drive is connected to the receptacle element and the receptacle element engages with a driver on the inner piece for the telescopic extension of the inner piece by vertical upward movement, and after reaching a level for access to the object, where a fixation of the inner piece with a locking mechanism occurs, it can be lowered into the inner piece. The inner piece of the housing is arranged in the region of each of the stacked levels with the open side facing the clean room next to at least one air passage opening, which is worked into a wall element provided as an interface with the clean room.
Guide elements are mounted on the guide rail, one of each being secured in a lower region of the inner piece, facing the wall element, and one in the upper region. An additional guide element, arranged on the guide rail between these two guide elements, is connected to the receptacle element, while the guide element secured in the upper region of the inner piece serves as a driver.
It is especially advantageous if the common drive fashioned as a spindle drive contains a tubular protection sheath, which separates the inner piece from a region in which rolling friction is produced by a spindle nut rotating about a spindle.
For air exit from the clean room, besides a loading and unloading opening additional air passageway openings are incorporated into the wall element underneath the loading and unloading opening at the height of the stationary outer piece of the housing.
At the inner piece, shields are provided to close the loading and unloading opening and the additional air passageway openings, while a closing of an opening occurs in the area of a level when the inner piece is arranged next to an opening in the area of the other level.
Advantageously, the receptacle element can move horizontally with a slide guide, which is carried by a holder, which is connected to the guide element of the receptacle element and to the spindle drive.
It is also advantageous for the movement of the receptacle element to be controlled and monitored by means of end position switches.
The invention, making use of an advantageous housing design, provides a mini-clean room that can be adapted with slight technical expense to different working heights and whose clean room conditions, unlike the known technical solutions, are effectively ensured simply by the clean room technology already present in the clean room of the processing station at any given working height The air flow through the mini-clean room occurs in such a way that areas of relative calm are largely eliminated within this space.